In the development of sanitary fixtures, such as bathtubs, spas and whirlpool tubs, independent wood inserts or separate pans have been used to form a leveling base for the tub fixture. Since a tub is generally inclined towards the drain, it is necessary to provide supports so that the upper surface of the tub is level. Typically, supports are attached to the fixture after manufacture and before or at installation. Sand or cement are alternative support materials which are poured at the desired location, upon which a tub fixture is forced into position.
These additional support structures and materials necessary for leveling and positioning tub fixtures cause delay in the installation process and increase labor. Moreover, higher cost results from the transportation of additional materials.
In the past, metal bathtubs have been fabricated with corrugations and grooves in them to provide support and prevent persons from slipping during use. U.S. Pat. No. 2,468,347 discloses a bathtub comprising inner and outer metal shells separated by insulating material. The outer shell has a plurality of corrugations projecting outwardly beyond the bottom surface of the outer shell to provide a bearing support for the tub. Similarly, U.S. Pat. No. 2,079,739 discloses a bathtub of cast iron, molded with grooves therein in which the surface is thereafter enameled or treated with the conformation of the grooves being preserved. The prior art structures are fabricated of metal to maintain rigidity and strength of complex and intricate shapes.
Attempts have been made to fabricate plastic bathtubs with reinforced floors. The reinforcement is typically provided by a support member connected to the underside of the bathtub floor. Conventional bathtub floor supports include a rigid particle board with a layer of urethane foam in combination with a styrene liner disposed intermediate the particle board and the underside of the floor. Holes are provided in the particle board for the incorporation of legs which raise the tub above the floor and provide space for plumbing pipes and easy access to the drain. Bonding of the styrene liner and the urethane foam to the particle board and the bathtub underside are labor intensive steps which require time and factory space.
U.S. Pat. No. 4,551,869 is directed at an attempt to decrease processing steps in the manufacture of plastic bathtubs. It relates to a plastic bathtub having a floor support including a top rigid panel having an upper side contoured to fit on the underside of the bathtub floor. A plurality of ribs are integrally formed with the top panel and extend therefrom in lattice formation. Seats or holes are provided in the lattice to receive and retain the legs which position the floor support and the plastic bathtub above the floor to provide clearance thereunder. The seats are varied in height along the length of the floor support to provide proper inclination of the bathtub toward the drain. Although the plastic support gives the plastic bathtub the needed rigidity to commercially compete with ceramic and fiberglass bathtubs, it is not integral to the bathtub and must be separately molded to the underside of the bathtub. The bathtub and the floor support are each independently molded from a plastic material. The floor support must then be welded to the plastic bathtub using a solvent cement. The attachment of the separate floor support adds an extra step to the manufacturing process. None of the related prior art shows bathtubs fabricated of non-metals and having integrally formed leveling runners or bottom supports, alone or in combination with mounting pockets for attaching an apron, or a motor mount for attaching a whirlpool motor.